U.S. Pat. No. 6,994,347 discloses a hit-scoring apparatus for shooting practice, comprising a target holder consisting of a body constituting the fixed first jaw and a moveable second jaw of a clamping device, the first jaw and the second jaw being electrically insulated from one another, and means adapted to produce a relative movement between the first jaw and the second jaw. A target panel is clamped between the first and second jaws and consists of a plurality of layers including an electrically conductive first layer and an electrically conductive second layer separated and spaced apart from the front layer by at least one electrically non-conductive layer. When the target panel is clamped between the first and second jaws of the target holder, separate electrical contacts are established between the first layer and the first jaw on the one hand, and between the second layer and the second jaw on the other hand, the first and second jaws being further connectable to a hit-scoring unit.
In order that the second layer makes electrical contact with the electrically conductive rear jaw, the metallic surface of the second layer must initially extend below the lower edge of the target and be folded at its lower edge during manufacture and secured by adhesive to the rear surface of the target. This can only be done manually and is therefore time-consuming and expensive.
The first layer is subdivided into different areas that are electrically insulated from each other and are each connected to a different one of the electrical contacts on the first jaw. The second layer provides a unitary conductive surface that is connected to the second jaw, which must be electrically conductive. An electronic circuit is mounted inside the fixed first jaw and detects when the two layers are shorted by a bullet. To this end, the electronic circuit must also be electrically connected to the conductive second jaw, this being done by a wire. Constant movement of the second jaw may subject the wire to fatigue, causing it to be break eventually and require replacement.
The different areas of the first layer allow the electronic circuit to discriminate between distinct areas of the target and provide feedback to the marksman as to where the bullet entered the target. The value of this feedback clearly depends on the number of distinct areas that can be separately isolated in the first layer. In theory, the second layer could also be subdivided into distinctive areas in order to improve the resolution of the discrimination but in practice this would require that the second jaw support separate contacts, each of which would then need to be connected to the electronic circuit by a respective wire.
In the target panel disclosed in U.S. Pat. No. 6,994,347, a discrete conductive area of the target connected to a contact pad in the apparatus that senses the short circuit caused by the bullet defines uniquely where the bullet strikes the target. This requires that the contact areas be spatially separated: the conductive tracks that route the contact areas to the contact pads cannot be allowed to cross a different contact area. This limits the measurement resolution of such a target since any given contact area cannot easily be further sub-divided into concentric areas owing to the difficulty in routing each sub-area to a separate contact pad. Provided that were sufficient contact pads available, it would be possible to sub-divide the contact areas and connect them by wires to the contact pads. However, this is not really practical since it significantly increases the cost of assembly.
It must be borne in mind that target practice is often carried out in hostile environments and the device must be sufficiently robust to withstand manhandling. The use of wires to connect the contacts of the moveable jaw to the second conductive layer of the target militates against the provision of additional channels that would allow better discrimination.
It would clearly be preferable to allow the second layer also to be subdivided in order to increase the resolution of the electronic circuit, while doing so in a manner that obviate the needs for wire connections from the moveable jaw to the discrimination circuitry.